Patent GB-470725-A (GB)
Title: Improvements in sensitising photographic gelatino-silver-halide emulsions and in manufacture of dyes therefor
IPC: G03C1/12
Filed: 1935-11-15
Abstract: Photographic emulsions are sensitized by means of dyes of the general formula <FORM:0470725/IV/1> wherein A = a divalent non-metallic atom, such as O or S, Z<1> and Z<2> represent substituents or non-metallic atoms forming part of a 5-or 6-membered heterocyclic nucleus or part of a homocyclic nucleus, or an acylated derivative of such dye.  Aryl may be phenyl, chlorphenyl, diphenyl or naphthyl.  The --(CH3)--chain may contain a halogen substituent.  The dyes are made by condensing a 5- or 6-membered heterocyclic or a homocyclic compound containing a nuclear --CH2-- group adjacent to a nuclear --CO-- or --CS-- group or an open chain compound containing a --CH2-- group adjacent to --C = A with a compound of the formula: <FORM:0470725/IV/2> wherein R and R<1> = aryl groups such as phenyl, chlorphenyl, diphenyl or naphthyl. A halogen substituent may be present in the chain.  These compounds are referred to as arylamino acrolein anils and may be used in the form of their salts.  Condensation agents specified are strong organic bases, e.g. di- and triethylamine, piperidine, N-methylpiperidine and triethanolamine, pyridine, acetic anhydride with or without potassium or sodium acetate, propionic or butyric anhydride.  In examples: (1) 3-ethylrhodamine is condensed with b -anilinoacrolein anil hydrochloride in presence of acetic anhydride to form 5-(g -acetanilido-allylidene)-3-ethylrhodamine, (2) the same two compounds are condensed in presence of piperidine and alcohol and the product acetylated, (3) 3-ethyl-2-thio-2 : 4-oxazoledione is condensed with b -anilinoacrolein anil hydrochloride as in (2) and the product acetylated, (4) 3-phenylrhodamine and b -anilino-a -bromoacrolein anil hydrobromide are condensed in presence of piperidine, (5) 2-diphenylamino-4-thiazolone is condensed with b -anilinoacrolein anil hydrochloride in acetic anhydride, (6) 3-ethyl - 2 - thio - 2 : 4 - oxazoledione is condensed with the anil hydrochloride in alcohol and triethylamine and the product acetylated, (7) 1-benzothiazyl-3-methyl-5-pyrazolone is similarly condensed in acetic anhydride, (8) 3-ethyl-1-phenyl-2-thiohydantoin is condensed as in (6) and the product acetylated, (9) 1 phenyl-3-methyl-5-pyrazolone is condensed with the anil hydrochloride in presence of acdtic anhydride and triethylamine. Heterocyclic compounds mentioned generally as starting materials are thiazolones, oxazolones,imidazolones, pyrazolones, thioindoxyls, barbituric acids, thiobarbituric acids, a 1 : 3-dihydroquinolone, dihydrocarbostyril, oxydihydroquinoxaline, benzo-b -morpholone and homophthalimide; homocyclic and open chain compounds specified are 1 : 3-cyclohexanedione, benzoylacetonitrile, cyanoacetanilide, malonic acid and pyruvic acid or esters thereof, acetoacetic ester, benzoylacetone, acetylacetone and indandione.  Details for preparing the sensitized emulsions are given and six spectrograms.  The dyes may be substituted in the nuclei by alkyl, alkoxy, chloro, bromo or amino groups.  Some of the dyes show small desensitizing effects together with sensitizing effects in another range of the spectrum. The dyes are also useful in the construction of light filters and as colouring matters for textiles, e.g. cellulose acetate artificial silk.  The dyes are probably tautomeric (formula given). Specifications 428,222 and 428,359 are referred to.  Reference has been directed by the Comptroller to Specifications 428,222 and 428,359.